Ophthalmological apparatus with a slit illumination for taking photographic views of the eye

ABSTRACT

A method and apparatus for analyzing the shape of the cornea of an eye, wherein narrow strips of the cornea surface are illuminated by a flat light beam and a picture of the illuminated profile of the illuminated profile of the cornea is taken by means of a camera of which the objective is perpendicular to the light beam, different profiles being taken by rotating said light beam and camera to different angular positions for succeeding exposures.

United States Patent 11 1 [111 3,762,803 Papritz Oct. 2, 1973 1OPHTHALMOLOGICAL APPARATUS WITH 350/87; 95/11 E, 11 M A SLITILLUMINATION FOR TAKING PHOTOGRAPHIC VIEWS OF THE EYE inventor: FranzPapritz, Niederscherli,

Switzerland Assignee: Haag-Street A.G., Liebefeld-Berne,

Switzerland Filed: Mar. 10, 1972 Appl. No.: 233,727

Related US. Application Data Continuation of Serv No. 37,670, May 15,1970, abandoned, which is a division of Ser. No. 599,851, Dec. 7, 1966,Pat. No. 3.519.338.

Foreign Application Priority Data Dec. 15, 1965 Switzerland 17305/65U.S.Cl ..35l/7, 351/14, 351/16 Int. Cl. A6lb 3/10, A611) 3/14 Field ofSearch 351/1, 7, l4, 16;

[56] References Cited UNITED STATES PATENTS 3,519,338 7/1970 Papritz351/7 Primary Examiner-David Schonberg Assistant Examiner-Paul A. SacherAtl0rneyEdward T. Connors [57] ABSTRACT A method and apparatus foranalyzing the shape of the cornea of an eye, wherein narrow strips ofthe cornea surface are illuminated by a flat light beam and a picture ofthe illuminated profile of the illuminated profile of the cornea istaken by means of a camera of which the objective is perpendicular tothe light beam, different profiles being taken by rotating said lightbeam and camera to different angular positions for succeeding exposures.

3 Claims, 2 Drawing Figures OPHTHALMOLOGICAL APPARATUS WITH A SLITILLUMINATION FOR TAKING PI-IOTOGRAPHIC VIEWS OF THE EYE The presentapplication is a continuation of now abandoned application Ser. No.37,670 filed May 15, 1970 which was a division of patent applicationSer. No. 599,851 filed Dec. 7, 1966, now U.S. Pat. No. 3,519,338 issuedJuly 7,1970.

This invention relates to a method and apparatus for analyzing the shapeof the cornea of an eye by repeatedly illuminating a narrow meridionalstrip of the cornea by means of a flat beam of light for illuminating aprofile of the cornea and taking a photographic picture of theilluminated portion of the cornea in a direction perpendicular to saidlight beam, the plane of said flat light beam and the camera for takingsaid picture being rotated together into different meridional angularposition between successive exposures for taking pictures of corneaprofiles at various angles. From the photographically registered corneaprofiles the shape of the cornea and particularly any irregularities ofthis shape may be analyzed subsequently without needing the patient, andcontact lenses may be prepared based on the analysis of the recordedcornea profiles. Of course, the recorded profiles may be analyzed forany other purpose.

The apparatus for recording the cornea profiles broadly comprises aphotographic camera having an objective and a film, illuminating meansincluding a light source for continuous illumination and a flashlightsource, a slit diaphragm for limiting the light falling from said lightsources into the eye to a flat beam, optical means for observation ofthe eye having an axis passing through the eye, said camera, saidilluminating 35 means and said means for observation of the eye beingrotatably mounted round said axis, an axis of incidence of the lightbeam into the eye, a fixing mark in this axis of incidence, the axis ofsaid objective being optically perpendicular and said film beingoptically parallel to said axis of incidence of the light beam.

One embodiment of the apparatus according to this invention isillustrated by way of example in the attached drawing wherein FIG. 1 isa sectional view of the apparatus and P10. 2 is a section along linell1l in FIG. 1 on a larger scale.

Theapparatus has" an incandescent lamp 1, a condenser 2, a slitdiaphragm 3, a plane mirror 4 and a illumination lens 5, these partsserving for continuously projecting a flat light beam into an eye 6. Theoptical elements are accommodated in a casing having a portion receivingthe lamp 1, condenser 2 and slit diaphragm 3. A second portion 21 of thecasing serves for accommodation of the mirror 4 and of a fixation mark 7displaceablc along the optical trace of the illuminating beam. The mark7 is fixed on a tube 22 extending through an opening of easing portion21 and guided on a bar 23.

A flash tube 9 is disposed between the condenser 2 and the slitdiaphragm 3 in a position parallel to the longitudinal extension of theslit. A flat beam of flash light may be projected into the eye 6 fromflash tube 9 through diaphragm 3, mirror 4 and lens 5. As shown in FIG.2 the flash tube 9 is supported in discs 24 screwed to the structure ofeasing portion 20. The diameter of the holes 25 ofdiscs 24 exceeds thediameter of the fixing screws 26 so that adjustment of the discs and ofthe flash tube supported therein in a direction transversal to thelongitudinal extension of the flash tube and of the slit of thediaphragm 3 respectively is possible when screws 26 are loosened. lt isthus possible to adjust the flash tube into a position opticallysymmetrical to the slit of the diaphragm and to the optical axis of thecondenser and of the lamp 1, so that the trace of rays of the lampillumination is not disturbed by any assymmetry of the flash tube.

The axis of the incident light beam includes an angle of 15 with theoptical axis 10 of an optical observing system having an objective I]and an ocular 12. The optical axis of this system is horizontal andpasses through the eye 6.

The objective ll of the observing system is accommodated in a tubularcarrier 27 rotatably mounted in a sleeve 28 of a support 29. The support29 is fixed on a table not shown in the drawing. The ocular of theobserving system is accommodated in a tube 30 fixed in the casing. Thecasing portions 20 and 21 are fixed on the tubular carrier 27 and may belocked in determined angular positions by means of a bracket 35engageable against the one rim portion of sleeve 28 by means of screw31. When the screw 35 is loosened for disengaging bracket 35 from sleeve28 the casing portions 20 and 21 may manually be rotated by seizing oneof parts 20 or 21 together with tubular carrier 27 into any desiredangular position, wherein parts 20, 21 and 27 may be locked again bymeans of bracket 35.

A support 36 is fixed at the fore end of carrier 27 in a bore of casingportion 21.

A plane mirror 13 fixed on support 36 is disposed in front of the eyeand at the side of the observing axis 10. The illuminated portion of thecornea of the eye 6 may be photographically recorded on the film 16 of aschematically illustrated camera 32 fixed in an opening of a casingportion 33 by means of a clamping ring 34. The trace of rays into thecamera passes from the cornea over mirror 13, an objective l4 andanother mirror 15. As shown in the drawing the trace of the rays betweenthe eye and the mirror 13 includes an angle of with the axis 8 of theincident beam. Further, the objective 14 includes an angle of 15 withthe trace of rays so that the axis of the objective 14 is opticallyperpendicular to the direction of incidence of the light beam. The planemirror 15 is so arranged that the film 16 which is in a planeperpendicular to the axis of observation 10 for practical reasons, isoptically parallel to the axis 8 of the incident light beam. The abovefacts may easily be verified by drawing the virtual positions of partsl4, l5 and 16 at the opposite side of the plane of mirror 13. Thevirtual position 14' of the objective is indicated in FIG. 1. The use oftwo mirrors l3 and 15 brings the further advantage that no reversal ofthe picture occurs.

Operation of the apparatus is as follows:

First the lamp 1 is switched on and the apparatus is so adjusted thatthe observation axis 10 is centered relatively to the eye 6. Afterwardsthe patient is instructed to look at the fixation mark 7, so that theeye is turned into the axis of incidence 8 of the light beam. In thiscase the flat light beam centrally enters into the eye and illuminates agreat circle of the cornea. As soon as the continuously observedillumination of the eye is centered as required the shutter of thecamera and the flash illumination are simultaneously actuated in amanner well known in the art, whereby a sharp image of one centralsection or profile of the cornea is obtained. The screw 31 is nowloosened and the apparatus is rotated round its axis into anotherangular position and is locked in the new position by means of screw 31and bracket 35, whereafter another picture of a cornea section is made.ln this manner a number of different sections or profiles of the corneamay be photographed and the exact form of the cornea may be determinedfrom the series of pictures. The grinding of the contact surface ofcontact lenses may be based on the pictures thus obtained. Since theaxis of the objective 14 is perpendicular to the direction of incidenceof the light and the film 16 is parallel to this direction of incidence,no distortion or shortening of the pictures of the cornea profileoccurs. Due to the inclination by of the incident light beam relativelyto the direction of observation a more favorable disposition of thetrace of rays and of the optical elements between the eye and the camerais obtained. Under all circumstances the mirror 13 may sufficiently beapproached to the face of the patient for forming a picture of thecornea without partial obstruction of the trace of rays Since the axisof the camera objective 14 is inclined by 15 to the trace of raysbetween the eye and the film, such that the eye is displaced from thecenter of the field of view of the objective and the point ofintersection of the axis of the objective and of the axis of lightincidence is outside the eye, the eye is seen by the camera under afavourable angle at which the full illuminated portion of the cornea isrecorded without obstruction by portions of the patients face.

As already mentioned, a picture on a reduced scale of the slit diaphragm3 is produced in the eye, this ailowing the use of a relatively longslit and of a correspondingly long flash tube so that a flashillumination of high intensity is obtained with simple and inexpensivemeans. On the other hand, the trace of rays of the continuousillumination by means of the lamp 1 is hardly influenced by the flashtube 9 and this tube may always be adjusted into a position for whichthe symmetry of the trace of rays of the continuous illumination is notdisturbed.

All optical axes shown in FIG. 1 are in a common plane, this allowing asimple, handy and flat construction of the apparatus What I claim is:

L An ophthalmological apparatus for taking photographic pictures of eyecornea profiles, said apparatus of the type including an optical systemfor observation of the eye and having an observation axis, aphotographic camera for taking pictures of the eye, a light source, anda slit diaphragm in optical alignment with said light source forillumination of a narrow meridional strip of the cornea with a flatlight beam, a structure for supporting a subassembly of said camera saidlight source and said slit diaphragm, bearing means allowing rotation ofsaid structure around said observation axis, and means for locking saidstructure in predetermined angular position, said camera including anobjective and a film, the plane of the film being optically parallel toand the axis of the objective being optically perpendicular to the axisof the light beam projected into the eye, the improvement wherein theconstruction is such that the axis of the objective intersects the axisof said light beam outside of the eye so that an angle is formed betweenthe axis of said objective and the trace of rays of said meridionalstrip passing from the eye to the objective whereby the full illuminatedportion of the cornea is recorded without obstruction by portions of thepatients face.

2. An apparatus according to claim 1, in which there is included a planemirror positioned parallel to said observation axis and extending fromsaid structure into the trace of rays between the eye and objective ofthe camera.

3. An apparatus according to claim 1, in which said optical system forobservation of the eye is accommodated in a horizontal tubular carrier,the axis of the light beam falling into the eye being inclinedrelatively to the axis of said tubular carrier the trace of the raysbetween the eye and the camera including an acute angle with the axis ofthe incident light beam directed into the eye.

1. An ophthalmological apparatus for taking photographic pictures of eyecornea profiles, said apparatus of the type including an optical systemfor observation of the eye and having an observation axis, aphotographic camera for taking pictures of the eye, a light source, anda slit diaphragm in optical alignment with said light source forillumination of a narrow meridional strip of the cornea with a flatlight beam, a structure for supporting a subassembly of said camera saidlight source and said slit diaphragm, bearing means allowing rotation ofsaid structure around said observation axis, and means for locking saidstructure in predetermined angular position, said camera including anobjective and a film, the plane of the film being optically parallel toand the axis of the objective being optically perpendicular to the axisof the light beam projected into the eye, the improvement wherein theconstruction is such that the axis of the objective intersects the axisof said light beam outside of the eye so that an angle is formed betweenthe axis of said objective and the trace of rays of said meridionalstrip passing from the eye to the objective whereby the full illuminatedportion of the cornea is recorded without obstruction by portions of thepatient''s face.
 2. An apparatus according to claim 1, in which there isincluded a plane mirror positioned parallel to said observation axis andextending from said structure into the trace of rays between the eye andobjective of the camera.
 3. An apparatus according to claim 1, in whichsaid optical system for observation of the eye is accommodated in ahorizontal tubular cArrier, the axis of the light beam falling into theeye being inclined relatively to the axis of said tubular carrier thetrace of the rays between the eye and the camera including an acuteangle with the axis of the incident light beam directed into the eye.